The invention relates generally to control systems, and more particularly to process control employing novel techniques for controlling the cooling of batch processes of a biofuel production plant.
A biofuel production plant may include one or more batch processes. An example of a batch process is the fermentation of a starch source to produce ethanol and other by-products in the presence of yeast and other enzymes in fermenters. Fermentation may be exothermic and the heat generated by fermentation may negatively affect the yeast. Thus, the contents of the fermenters are cooled to maintain the temperature of the fermenter within a range acceptable for the yeast. The biofuel production plant may use a variety of methods for cooling the fermenters, which may include circulating the fermenter contents through a heat exchanger cooled by water. Several sources of cooling water may be used and the sources may differ in terms of temperature and available flow rate. In addition, each of the fermenters of the biofuel production plant may be operating at different points of a batch cycle. Thus, the plant-wide consumption of cooling water varies and there may not be sufficient cooling water to provide maximum cooling to all fermenters simultaneously. Existing methods of controlling cooling in biofuel production plants suffer from disadvantages that may result in decreased ethanol production and inefficient use of yeast.